Catheters and methods for performing cardiac diagnosis and treatment

ABSTRACT

A system and method for cardiac diagnosis and treatment inserts the distal end of a catheter into a heart chamber. The distal end of the catheter supports at least one electrode. The catheter has a fluid flow conduit extending through it. The conduit has a valve that prevents fluid flow from the heart chamber into the conduit in response to in vivo pressure generated during heart systole and diastole. The valve permits fluid flow from the conduit into the heart at a pressure above the in vivo pressure. In use, the catheter locates the electrode in contact with a portion of the endocardium, and fluid is conducted from an external source through the conduit at a pressure above the in vivo pressure to flush the area surrounding the electrode.

FIELD OF THE INVENTION

The invention relates to catheters and related systems and methods formapping and ablating the interior regions of the heart for diagnosis andtreatment of cardiac conditions.

BACKGROUND OF THE INVENTION

Cardiac mapping is used to locate aberrant electrical pathways andcurrents emanating within the heart. The aberrant pathways cause thecontractions of the heart muscle to take on peculiar and lifethreatening patterns or dysrhythmias.

Intracardiac mapping requires the careful positioning of an array ofmultiple electrodes within the heart. Various structures for thesemultiple electrode mapping arrays have been developed or proposed.

For example, Hess U.S. Pat. Nos. 4,573,473 and 4,690,148 and Desai U.S.Pat. No. 4,940,064 show the use of generally planar mapping arrays.Chilson U.S. Pat. No. 4,699,147 shows the use of a three dimensionalbasket mapping array. Gelinas U.S. Pat. No. 4,522,212 shows a springapart array of electrode supporting fingers.

Regardless of the type of mapping array used, the physician is calledupon to remotely move and manipulate the array within the heart invarious ways. First, the physician must maneuver the array through amain vein or artery into a selected heart chamber. Then, the physicianmust locate the array at the desired endocardial location. Then, thephysician must further move the array at the desire location to assurethat all aberrant electrical pathways, if present, are located.

The development of prior mapping arrays has focused upon therequirements of mapping function itself. The prior development hasoverlooked the important need to continuously wash the area around theelectrodes during the procedure.

The flushing action clears blood and other body fluids away from theelectrode, so that reliable mapping signals can be obtained and/or thedesired ablation energy can be applied, without attentuation anddisruption.

SUMMARY OF THE INVENTION

The invention provides improved apparatus and methods for cardiacdiagnosis and treatment. The apparatus and methods provide a flushingaction that clears blood and other body fluids away from the distal endof a catheter, so that reliable mapping signals can be obtained and/orthe desired ablation energy can be applied through an associatedelectrode, without attentuation and disruption.

One aspect of the invention provides a probe that includes a catheterhaving a distal end for insertion into a heart chamber. The distal endof the catheter supports at least one electrode. A fluid flow conduitextends through the catheter for conducting fluid from a external sourcethrough the distal catheter end. A valve member at the distal catheterend prevents fluid flow from the heart chamber into the conduit whilepermitting the fluid flow through the conduit into the heart chamber.

Another aspect of the invention provides a method for cardiac diagnosisand treatment that inserts the distal end of a catheter into a heartchamber. The distal end of the catheter supports at least one electrode.The catheter has a fluid flow conduit extending through it. The conduithas a valve element that prevents fluid flow from the heart chamber intothe conduit in response to in vivo pressure generated during heartsystole and diastole while permitting fluid flow from the conduit intothe heart at a pressure above the in vivo pressure. The method locatesthe electrode in contact with a portion of the endocardium. The methodconducts fluid from an external source through the conduit at a pressureabove the in vivo pressure, thereby opening the valve element, to flushthe area surrounding the electrode.

The fluid can be, for example, saline and be used to flush the regionaround the electrode to keep it free of tissue buildup and blood. Thefluid can also be heparin or another anticoagulant and be used toactively reduce the incidence of coagulation during the procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an endocardial mapping system thatembodies the features of the invention;

FIG. 2 is a top view of the probe associated with the system shown inFIG. 1, showing the operation of the steering mechanism;

FIGS. 3 and 4 are side elevation views of the probe associated with thesystem shown in FIG. 1, showing the operation of the deploymentmechanism for the mapping array;

FIGS. 5 to 7 are side elevation views of the probe associated with thesystem shown in FIG. 1, showing the operation of the mechanism foropening and shaping the mapping array;

FIG. 8 is a side elevation view of the probe associated with the systemshown in FIG. 1, showing the operation of the mechanism for rotating themapping array;

FIG. 9 is an exploded side elevation view of the probe associated withthe system shown in FIG. 1;

FIG. 10 is an enlarged side section view of the interior of the probebody shown in FIG. 9, when assembled, where the proximal end of thecatheter joins the main probe body;

FIG. 11 is an enlarged side section view of the interior of the tip ofthe probe handle shown in FIG. 9, when assembled;

FIG. 12 is an enlarged side sectional view, with portions broken away,of the mapping basket associated with the system shown in FIG. 1;

FIG. 13 is an enlarged perspective view, with portions broken away, of acylindrical electrode support spline that the mapping basket shown inFIG. 12 can use;

FIG. 14 is a greatly enlarged sectional view of the cylindricalelectrode support spline taken generally along line 14--14 in FIG. 13;

FIG. 15 is an enlarged perspective view of a rectilinear spline that themapping basket shown in FIG. 12 can use;

FIG. 16 is a perspective view of the rectilinear spline shown in FIG. 15before attachment of the electrodes;

FIG. 17 is an enlarged perspective view of an alternative embodiment ofa rectilinear spline that the mapping basket shown in FIG. 12 can use;

FIG. 18 is an exploded perspective view of the rectilinear spline shownin FIG. 15, showing its multiple conductive and nonconductive layers;

FIG. 19 is a schematic exploded side view of the multiple conductive andnonconductive layers of the rectilinear spline shown in FIG. 18;

FIG. 20 is an enlarged perspective view, largely schematic, of the solidstate circuit tube and one of eight microconnector chips associated withthe mapping assembly shown in FIG. 1;

FIG. 21 is top view of the electrical attachment between microconnectorchips and the solid state circuit tube shown in FIG. 20;

FIG. 22 is an enlarged perspective view, largely schematic, of analternative embodiment for the solid state circuit tube and themicroconnector chips associated with the mapping assembly shown in FIG.1;

FIG. 23 is a schematic view of a power supply and signal control circuitfor the microconnector shown in FIGS. 20 and 21;

FIG. 24 is a schematic view of an alternative power supply and signalcontrol circuit for the microconnector shown in FIG. 22;

FIG. 25 is a top view of the interior of the steering mechanismassociated with the probe shown in FIG. 1:

FIG. 26 is a view of the distal end of an alternative catheter having amapping assembly that is located using a guide wire, instead of asteering mechanism;

FIG. 27 is an enlarged view of the end cap of the mapping assembly shownin FIG. 26;

FIG. 27A is an enlarged cross sectional view taken along line 27A--27Aof FIG. 27;

FIGS. 28 and 29 are side section views of an alternative deployablemapping assembly using an inflatable bag;

FIGS. 30A and B are side section views of an alternative deployablemapping assembly using a flexible sail-like body;

FIGS. 31A/B/C are side section views of an alternative deployablemapping assembly using a central spline with random electrode supportfilaments;

FIGS. 32A and B are side section views of an alternative deployablemapping assembly using a foam body;

FIG. 33 is a side section view of the base member of a dynamic mappingassembly that embodies the features of the invention shown in acontracted condition;

FIG. 34 is a side section view of the dynamic mapping assemblyassociated with the base member shown in FIG. 33 in a contactedcondition;

FIG. 35 is a side section view of the base member of a dynamic mappingassembly that embodies the features of the invention shown in anexpanded condition; and

FIG. 36 is a side section view of the dynamic mapping assemblyassociated with the base member shown in FIG. 35 in an expandedcondition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an endocardial mapping system 10 that embodies the featuresof the invention. The system 10 includes a hand-held probe 12 and anassociated controller 14.

The probe 12 has a handle 16 and an attached flexible catheter 18. Thecatheter 18 slidably carries within an interior lumen a mapping assembly20 that is extendable out of the distal end of the catheter.

The mapping assembly 20 establishes a three dimensional array ofelectrodes 22. In use, the mapping assembly 20 records the activationtimes, the distribution, and the waveforms of the electrical charges orpotentials that trigger the pumping action of the heart muscle.

Leads 24 pass through the lumen of the catheter and connect the mappingassembly 20 to the controller 14. The controller 14 receives andprocesses the potentials recorded by the electrodes 22 on the mappingassembly 20. An attached CRT 26 visually presents the processed data forviewing by the attending physician. The controller 14 also has a printer28 for presenting the processed data in strip chart form.

The physician positions the mapping assembly 20 by maneuvering thecatheter 18 through a main vein or artery (which is typically thefemoral artery) into a selected heart chamber. During this time, themapping assembly 20 is carried in a compact, folded away position withindistal end of the catheter 18 (as FIG. 3 shows). The physician canobserve the progress of the distal catheter end using fluoroscopic orultrasound imaging, or the like.

When the physician places the distal end of the catheter 18 in thedesired endocardial location, he/she manipulates the control mechanismsof probe 12 to deploy and open the mapping assembly 20 into the desiredthree dimensional array 22 (as FIG. 1 shows).

The controller 14 analyses the signals received from the electrodes 22to locate abnormal foci in the tissue that disrupt the normal heartrhythm and can cause cardiac arrhythmia. Once located, the physician canremove or destroy the abnormal foci by ablation to restore a normalheart rhythm. A separate RF or microwave ablation probe (not shown) canbe used for this purpose. Alternatively, the mapping array 22 can itselfinclude one or more ablating electrodes.

According to one aspect of the invention, the probe 12 includes fourindependent control mechanisms for the physician to manipulate incarrying out the multiple steps of the mapping procedure just generallyoutlined. The control mechanism are centrally located on the handle 16to simplify error free manipulation of the catheter 18 and associatedmapping assembly 20.

The first control mechanism 30 deflects the distal end of the catheter18 (as FIG. 2 shows). This allows the physician to remotely point andsteer the distal end of the catheter 18 within the body.

When the mapping assembly 20 is deployed, the first mechanism 30 canalso be used to point and steer the mapping assembly 20 itself. Thisallows the physician to remotely maneuver the mapping assembly 20 intoposition against endocardial tissue.

The second mechanism 32 controls the deployment of the mapping assembly20. The second mechanism 32 controls deployment of the mapping assembly20 from a retracted position within the distal end of the catheter 18(shown in FIG. 3) to an operating position outside the catheter 18(shown in FIG. 4).

When retracted, the mapping assembly 20 occupies a low profile positionthat does not hinder the maneuvering within the body. When deployed inthe operating position, the mapping assembly 20 can be opened to carryout its signal mapping function.

The third mechanism 34 opens the mapping assembly 20, when deployed. Thethird mechanism 34 moves the mapping assembly 20 between its completedclosed, folded position (shown in FIG. 4) and an completely opened,unfolded position (shown in FIG. 5).

In the illustrated and preferred embodiment, the third mechanism 34 alsocontrols the three dimensional shape of the mapping assembly 20. In thisarrangement, the physician can remotely shape the mapping assembly 20 bymanipulating the third mechanism 34.

In the illustrated embodiment, the third mechanism 34 progressivelychanges shape of the mapping assembly 20 from an elongated ellipse (asFIG. 7 shows), to an intermediate sphere (as FIG. 5 shows), to a toroid(as FIG. 6 shows). Using the third mechanism 34 for this purpose, thephysician can alter the shape of the mapping assembly 20 to more closelymatch the particular endocardial profile to be recorded.

The fourth mechanism 36 controls the rotational position of the mappingassembly 20 independent of the rotational position of the catheter 18(as FIG. 8 shows). In other words, the fourth mechanism 36 rotates themapping assembly 20 without rotating the catheter 18.

Using the fourth mechanism 36, the physician can rotate the mappingassembly 20 within the heart, without otherwise rotating the catheter 18within the access vein or artery.

The structural features of the catheter, the mapping assembly 20, andthe associated control mechanism 30-36 can vary. These features will nowbe discussed in greater detail, as they appear in the illustratedembodiments.

1. The Probe Handle

In the illustrated embodiment (as FIGS. 9 to 11 show), the probe handle16 includes a main body 38, a base 40, and a tip 42. The handle 16 andits component parts can be constructed from various durable metal orplastic materials. In the illustrated embodiment, the handle 16 ismostly molded plastic.

The main body 38 has an interior channel 44 (see FIG. 10). A junctiontube 46 is secured within the interior channel 44. The proximal end ofthe catheter 18 is, in turn, joined by adhesive or the like to the frontend of the junction tube 46. As FIG. 10 also shows, the interior channel44 also includes an annular groove 48 near its distal end, where theseparately molded tip 42 is attached.

The handle base 40 is a premolded extension of the main body 38 (seeFIG. 9). The base 40 is generally flat and carries a steering member 50.As will be described in greater detail later, the steering member 50houses an actuator for the first control mechanism 30 to point and steerthe distal end of the catheter 18.

The steering member 50 is also movable within a track 52 fore and aftupon the base 40 (see FIGS. 1 and 2 also). A telescopic shaft 54connects the steering member 50 to the rear end of the junction tube 46.Fore and aft movement of the steering member 50 within the track 52expands and collapses the telescopic shaft 54.

As will also be described in greater detail later, the fore and aftmovement of the steering member 50 actuates the third control mechanism34 to open and (in the preferred embodiment) shape the mapping assembly20.

The handle tip 42 extends from the front of the main body 38. Itincludes a proximal flanged end 56 which seats within the annular groove48 of the main body channel 44 (as FIGS. 9 and 10 show).

The flanged end 56 freely rotates within the annular groove 48. Thisallows the handle tip 42 to rotate relative to the main body 38. As willbe described in greater detail later, the relative rotation between thehandle tip 42 and main body 38 forms the basis for the fourth controlmechanism 36.

As FIG. 10 shows, the handle tip 42 includes a center bore 58 that isaxially aligned with the interior channel 44 of the main body 38. Acarriage 60 moves within the center bore 58. As will be described ingreater detail later, the movable carriage 60 actuates the secondcontrol mechanism 32 to control deployment the mapping assembly 20.

2. The Catheter

The catheter 18 includes a flexible tube 62 having an interior bore orlumen 64 (see FIG. 12). The proximal end of the flexible tube 62 extendsthrough the center tip bore 58 and into main body channel 44, where itis joined to the junction tube 46 (as FIG. 10 shows).

The flexible tube 62 may constructed in various ways. For example, itmay comprises a length of stainless steel coiled into a flexible springenclosing the interior bore 64.

In the illustrated and preferred embodiment, the tube 62 comprises aslotted, stainless steel tube. An array of slots 66 subtends the tubealong its length. The slots 66 subtend less than one circumference ofthe shaft at an angle of between 270 to 300 degrees. The slots 66 arealso preferably radially offset one from the other by about 30 to 120degrees.

The slots 66 provide flexibility along the length of the tube 62. Thepattern and arrangement of the slots 66 impart the necessary flexibilityand torque transmission capabilities to tube 62.

Further details of the slotted tube 62 are disclosed in pendingLundquist U.S. patent application Ser. No. 07/657,106 filed Feb. 15,1991 and entitled "Torquable Catheter and Method."

The catheter 18 also includes a sheath 68 enclosing the flexible tube62. The sheath 68 is made from a plastic material, such as a polyolefin,polyurethane or polydimethylsiloxane. The sheath 68 has an innerdiameter that is greater than the outer diameter of the tube 62. In thisway, the sheath 68 slides along the outside of the tube 62 in responseto the second control mechanism 32, to selectively enclose or expose theappended mapping assembly 20.

3. The Mapping Assembly

The mapping assembly 20 may take various different forms. In theembodiment illustrated in FIGS. 1 to 9, the mapping assembly 20comprises a variably shaped basket 70, the details of which are bestshown in FIG. 12.

The mapping basket 70 comprises a base member 72 attached to the distalend of the flexible catheter tube 62. The mapping basket 70 alsoincludes an end cap 74. Generally flexible electrode supports or splines76 extend in a circumferentially spaced relationship between the basemember 72 and the end cap 74. The splines 76 carry the spaced sensingelectrodes 22. Electrodes can also be located on end cap 74.

The outer diameters of the base member 72 and end cap 74 are less thanthe interior diameter of the movable sheath 68 (FIG. 12 shows thisrelationship with respect to the base member 72, but the end cap 74 isshown enlarged to better show the details of its construction). End cap74 is preferably rounded or dome-shaped as shown. In this way, whenmoved toward the distal end of the flexible tube 62, the sheath 68 movesover and captures the mapping basket 70 (in the flattened position) andonly the dome-shaped end of cap 74 is exposed. When moved the oppositeway, the sheath 68 exposes the mapping basket 70 for use. In addition toelectrodes located on splines 76A, one or more electrodes can also belocated on end cap 74 to provide for additional signal measuringcapability.

Still referring to FIG. 12, the mapping basket 70 further includes agenerally stiff control wire 78. The distal end of the control wire 78is attached to the end cap 74. From there, the control wire extendsthrough the base member 72 and the bore 64 of the tube 62 for attachmentto the third control mechanism 34, as will be described later.

Axial movement of the control wire 78 in response to actuation of thethird control mechanism 34 moves the end cap 74 either toward or awayfrom the base member 72. This flexes the splines 76 to vary the shape ofthe basket 70.

The splines 76 of the mapping basket 70 shown in FIG. 12 can assumevarious cross sectional shapes. The details of representativeconstructions will be discussed next.

A. The Basket Splines (i) Cylindrical Splines

FIGS. 13 and 14 show a spline 76A having a cylindrical cross section.The spline 76A carries the sensing electrodes 22 axially spaced alongits length (six electrodes 22 are shown for the sake of illustration).The proximal end of the spline 76A includes an eyelet 80 for attachmentto a pin on the base member 72. The distal end of the spline carries ahook 82 for quick connection to circumferentially spaced openings 84 onthe end cap (as FIG. 12 shows). Of course, other quick connect couplingmechanisms can be used.

The cylindrical spline 76A can have an open interior passage forconducting individual signal wires connected to the sensing electrodes22.

However, in the embodiment shown in FIGS. 13 and 14, the body of thecylindrical spline 76A is solid. It comprises multiple individual layersor substrates, as FIG. 14 shows. Alternating layers 86 are coated withan electrically conductive material, like platinum. Intermediate layers88 of nonconductive material, like polyimide, separate the conductivelayers 86.

The layers 86 and 88 can be applied, for example, by ion beam assisteddeposition (IBAD), or similar vapor deposition techniques. In theillustrated embodiment, each layer is about 0.0005 inch to 0.002 inchthick.

As FIG. 13 shows, an individual signal wire 90 is attached to eachconductive layer 86. The signal wires 90 exit the proximal end of thespline 76A and are joined to a microconnector 92, the details of whichwill be described in greater detail later.

The number of conductive layers 86 equals the maximum number ofelectrodes 22 that the spline 76A carries. In the illustratedembodiment, each cylindrical spline 76A carries a maximum of 12 sensingelectrodes, so there are 12 conductive layers 86 and 12 signal wires(FIG. 13 shows only a portion of the electrodes 22 and the signal wiresfor the sake of illustration).

In the illustrated embodiment, each sensing electrode 22 comprises aflexible substrate such as a silicone rubber body that has been coatedby IBAD with platinum. Each sensing electrode is slipped into positionover the spline 76A and there fastened by adhesive or the like.Alternatively, the rubber bodies can be molded in place over the splineand subsequently coated with a conductive layer by IBAD.

A wire or pin 94 made of electrical conductive material (such asplatinum) is inserted through each electrode 22 and into the body of thespline 76A. Each pin 94 is coated with an insulating material, exceptfor its head end and its tip end.

As FIG. 14 shows, the pins 94 have different prescribed lengths, so thattheir tip ends reach different conductive layers 86. Each pin 94individually conducts the signals received by its associated sensingelectrode 22 to one conductive layer 86. In this way, the signals sensedby each electrode 22 is transmitted by a different conductive layer 86to the associated signal wire 90.

(ii) Rectilinear Splines

FIG. 15 shows an electrode support spline 76B having a general flat,rectilinear cross section.

Unlike the cylindrical spline 76A shown in FIG. 13, the rectilinearspline 76B has anisotropic stiffness. It exhibits the flexibility todeflect or bend in one plane along its longitudinal X axis 96 (in thedirection of the Y axis as shown by arrows in FIG. 15). However, itexhibits stiffness to resist flexing or twisting about its longitudinalX axis 96 in the direction of the Z axis.

As FIG. 15 shows, each rectilinear spline 76B carries sensing electrodes22 axially spaced along its longitudinal axis 96. Like the cylindricalspline 76A, the proximal end of the rectilinear spline 76B includes aneyelet 80 for attachment to the basket base member 72. The distal end ofthe spline 76B carries a hook 82 for quick connection to thecircumferentially spaced openings 84 on the basket end cap 74 (see FIG.12).

When so connected, the anisotropic stiffness of each rectilinear spline76B resists twisting about its longitudinal axis 96. This keeps thebasket 70 torsionally rigid. The adjacent splines 76B are retained inthe desired circumferentially spaced relationship.

Still, axial movement of the control wire 78 will flex each of therectilinear splines 76B centrally outwardly along their longitudinalaxes 96 in the direction of their Y axes. This will alter thecircumferential shape of the basket 70 (as FIGS. 5 to 7 show).

Due to their anisotropic stiffness, adjacent splines 76B will resisttwisting. The assembled basket 70 will therefore also resist twistingand will retain a desired symmetrical three dimensional shape about itslongitudinal axis.

In the embodiment shown in FIG. 15, the spline 76B comprises multipleconductive layers 98 separated by intermediate nonconductive layers 100(as FIGS. 18 and 19 best show). The conductive layers 98 are coated withan electrically conductive material, such as platinum. The conductivelayers are preferably 0.005 to 0.002 inch in thickness. Thenonconductive layers 100 are made of a nonconductive material, such as apolyimide or similar polymeric material.

As FIGS. 18 and 19 show, an electrode wire 102 is soldered to eachconductive layer 98. The individual electrode wire 102 for oneconductive layer 98 is axially spaced apart from the electrode wire 102for the next conductive layer 98. As FIGS. 18 and 19 also show, theelectrode wires 102 from the lower conductive layers 98 pass throughplated through openings 102 in successive upper conductive andnonconductive layers 98 and 100 to exit the top surface of the spline76B (as FIG. 16 also shows). There, an electrode 22 is soldered to eachelectrode wire 102.

As FIGS. 15; 16; 18; and 19 show, the proximal ends of the variousconductive and nonconductive layers 98 and 100 are preferably arrangedin stepwise fashion. This exposes each conductive layer 98 to facilitateconnection of the signal wires 90 by soldering.

In an alternative arrangement (as FIG. 17), the electrodes 22 are vapordeposited on the surface of the rectilinear spline 76C. In thisarrangement, the surface of the spline 76C also carries a solid stateprinted circuit 104 formed by either ion deposition or etching. Thecircuit 104 conducts signals from the individual electrodes 22 toindividual signal wires 90 attached at the proximal end of the spline76C. An eyelet 80 and a hook 82 provide for quick attachment of thespline 76C between the basket base member 72 and end cap 74, aspreviously described.

B. The Microconnector

The multiple signal wires 90 leading from the sensing electrodes can bebundled together and passed as individual wires through the bore 64 ofthe flexible guide tube 62 for attachment to the controller 14. Laserwelding can be used to minimize the cross sectional area of theelectrical connectors.

In the illustrated and preferred embodiment, the number of electricallyconductive wire leads passing through lumen 64 is minimized by usingsolid state microconnector 92 in the base member 72 (see FIG. 12). FIGS.20 to 24 show the details of the microconnector 92.

As FIG. 20 shows, the microconnector 92 includes one microprocessor chip106 for each electrode support spline 76 in the basket 70. FIGS. 20 to24 assume an array of 56 sensing electrodes 22 on the basket 70. In thisarray, there are eight splines 76, with each spline 76 holding sevensensing electrodes 22. In this arrangement, the microconnector 92includes eight individual chips 106 (as FIG. 21 shows), with sevenelectrode signal wires 90 attached to each chip 106 (as FIG. 20 shows).

The chips 106 serve as switches controlled by the controller 14. Eachchip 106 receives seven individual signals, one from each electrode 22on the associated spline 76. Each chip 106 transmits only a selected oneof the electrode signals at a time to the controller 14, subject to theswitching signals that the controller 14 generates. The switchingsignals of the controller 14 thereby multiplex the electrode signalsthrough the microconnector 92. This reduces the number of electricalpathways required through lumen 64.

As FIG. 20 also shows, each chip 106 includes an I/O buss 108 comprisinga power (+) contact 110 and a power (-) contact 112. The power contacts110 and 112 receive power from a supply 130 within the controller 14.The I/O buss 108 also includes an input switching (or control) contact114, which receives the switching signals from the signal generator 132within the controller 14 to select the input signal wire to be sampled.The control contact 114 can also receive ablation energy through thesignal generator 134 from a source 135, to thereby use one or more ofthe associated sensing electrodes for tissue ablation.

The I/O buss 108 further includes an output signal contact 116 fortransmitting the selected electrode signal to the signal processor 134within the controller. FIGS. 23 and 24 diagrammatically show thecomponents 130; 132; and 134 of the controller.

The power, control, and output signals of each chip 106 are transmittedto and from the buss 108 along an electrical conduction conduit 118carried within the lumen 64 of tube 62. The electrical conduit 118 canbe variously constructed. It can, for example, comprise coaxial cable.

In the illustrated embodiment (see FIG. 21), the conduit 118 comprises aMylar polyester tube. The surface of the tube 118 carries a solid stateprinted circuit 120 formed by either ion deposition or etching.

The specific configuration of the circuit 120 deposited on the tubularconduit 118 can vary. In the embodiment shown in FIG. 23, the circuit120 comprises 32 individual conducting paths that extend in a helicalarray deposited about the axis of the tube. As FIG. 20 also shows, thearray includes one power (+) line 122 and one power (-) line 124 foreach chip 106 (for a total of 16 power (+) and (-) lines). These linesare connected to the power supply 130 within the controller 14.

The array shown in FIGS. 20 and 23 also includes one input control line126 and one signal output line 128 for each chip 106 (for 16 additionallines, comprising a total of 32 conducting lines). These lines 126 and128 are connected, respectively, to the signal multiplexing controlcircuit 132 and to the signal processing circuit 134 of the controller14.

As FIG. 20 and 21 show, a stainless steel ferrule 136 electricallyinterconnects the lines of the circuit 120 with the microconnector 92.The ferrule is located within the distal end of the Mylar polyester tube118. The ferrule 136 has a prescribed array of 32 cone points 138. Thecone points 138 electrically interconnect the appropriate power (+) and(-) lines 122 and 124, the control input line 126, and the signal outputline 128 to the associated contacts 110/112/114/116 of the I/O buss 108of each chip 106.

In an alternative arrangement (as FIGS. 22 and 24 show), the circuit 120carried on the tube 118 is reduced to 18 lines. This circuit 120 alsoextends in a helical array deposited about the axis of the tube 118.This array carries only one power (+) line 122 and one power (-) line124, connected to the power supply 130. As FIG. 24 shows, the distalends of the power (+) line 122 and the power (-) line 124 encircle thedistal end of the tube 118 in axially spaced loops.

In the particular array shown in FIG. 24, the loop of the power (+) line122 is located closer to the distal end of the tube 118 than the loop ofthe power (-) line 124 (see FIG. 22, also).

The array carried by the tube 118 also includes one input control line126 and one signal output line I 28 for each chip 106, for a total of 16additional lines. As before described, these lines 126 and 128 areconnected to the multiplexing and signal analyzing circuits 132 and 134of the controller 14 (as FIG. 24 shows). As FIG. 22 shows, the lines 126and 128 terminate on the distal end of the tube 118 below the power (+)and power (-) loops 122 and 124 just described.

In this arrangement (as FIG. 22 shows), a portion of the I/O buss 108 ofeach chip 106 is arranged circumferentially. The top two contacts 110and 112 comprise the power (+) and power (-) contacts, respectively.These are commonly connected by cone points 138 on the ferrule 136 tothe power (+) and power (-) loops 122 and 124, as FIG. 22 shows.

The bottom two contacts 114 and 116 of the I/O buss 108 comprise thecontrol input and signal out leads. These contacts 114 and 116 arecircumferentially arranged below the axial power contacts 110 and 112.The cone points 138 on the ferrule 136 appropriately connect the controlinput line 126 and the signal output line 128 to these circumferentiallyarranged contacts 114 and 116 of the I/O buss 108, as FIG. 22 shows.

4. The Probe Control Mechanisms A. The Steering Control Mechanism

In the illustrated arrangement shown in FIG. 1, the first probe controlmechanism 30 occupies the interior of the steering member 50. FIG. 25shows further details of this construction.

The first mechanism 30 includes a rotating cam wheel 140 housed withinthe steering member 50. A lever 142 on the exterior of the steeringmember 50 (see FIG. 1) is attached to the interior cam wheel 140.Movement of the steering lever 142 by the user rotates the cam wheel140.

As FIG. 25 shows, the cam wheel 140 carries a fastener 144 between itsright and left side surfaces. Fastener 144 holds the proximal ends ofright and left probe steering wires 146 and 148, which are soldered tothe interior of the fastener 144.

The steering wires 146 and 148 extend from the opposite ends of thefastener 144 and along the associated right and left sides of the camwheel 140. The steering wires 146 and 148 exit the front of the steeringmember 50 through the interior bore of a tension screw assembly 150,passing through the telescopic shaft 54 and into the junction tube 46,as FIG. 10 shows.

The steering wires 146 and 148 extend further along within the flexibleshaft bore 64. Near the distal end of the tube 62, the steering wires146 and 148 pass outside the bore 64 through exit holes (not shown). AsFIG. 12 shows, solder connects the end of the left steering wire 148 tothe left side of the distal end of the flexible tube 62. Likewise,solder connects the end of the right steering wire 146 to the right sideof the distal end of the flexible tube 62.

Left rotation of the cam wheel 140 pulls the left steering wire 148 tobend the distal end of the tube 62 to the left. Likewise, right rotationof the cam wheel 140 pulls the right steering wire 146 to bend thedistal end of the tube 62 to the right.

In this way, the first control mechanism 30 steers the distal end of theflexible tube 62 and, with it, the attached mapping basket 70 (as FIG. 2shows).

It should be appreciated that, instead of using an active onboardmechanism for steering the flexible tube 62, a wire can be used to guideand position the distal end of the tube 62 in the heart. FIGS. 26 and 27show this alternative, over-the-wire embodiment, which lacks an onboardsteering mechanism.

In the embodiment shown in FIGS. 26 and 27, the probe 10A includes aninterior guide wire 152. The guide wire 152 extends from the handle (notshown), through the bore 64 of the flexible tube 62, passing through acentral guide tube 154 in the mapping basket 70.

In use, the physician first maneuvers the guide wire 152 through themain vein or artery into a selected heart chamber. Then, the physicianpasses the tube 62 of the probe 10A with the attached mapping basket 70over the guide wire 152 into position.

In this embodiment (as FIG. 26 shows), the probe 10A still preferablyincludes a slidable sheath 68 for temporarily enclosing the mappingbasket 70 while being guided over the wire 152 into position (as FIGS. 3and 4 show).

As FIG. 27 shows, the over-the-wire probe 10A also preferably includes avalve 156 in the guide tube 154. The valve 156 prevents the back flow ofblood and other fluids within the heart chamber into the guide tube 154and the interior regions of the probe 10A under the influence of theheart diastole and systole pressures generated in vivo within the heart.As best seen in FIG. 27A valve 156 is formed of an elastomer such as asynthetic rubber formed inside of a polyimide tube 157. The elastomericbody is formed into three segments enclosing wire 152 by means of threecuts 159. The elastomer displaces upon introduction of wire 152, forminga fluid tight seal about the wire 152.

The valve 156 thereby blocks the back flow of fluids into the catheterin response to in vivo heart pressures.

B. The Mapping Assembly Development Mechanism

In the illustrated arrangement, the second mechanism 32 occupies the tip42 of the probe handle 16. FIG. 11 shows further details of thisconstruction.

As FIG. 11 shows, the second mechanism 32 includes a carriage 60 thatmoves within the center bore 58 of the handle tip. The carriage 60includes an opening 158 concentric with the axis of the center bore 58,through which the flexible tube 62 passes. As FIG. 11 shows, the outerdiameter of the flexible tube 62 is less than the inner diameter of thecarriage opening 158.

The carriage member 60 has an exposed actuator 160 that extends throughan elongated slot 162 in the handle tip (as FIGS. 1 and 2 also show).The slot 162 extends along the axis of the center bore 58. Fore and aftmovement of the actuator 160 by the user moves the carriage member 60within the center bore 58 axially over the flexible tube 62.

As FIG. 11 further shows, the proximal end of the sliding sheath 68 isfastened by adhesive or the like to the carriage 60. Carriage movementas just described will thus also slide the attached sheath 68 axiallyover the flexible tube 62.

When the actuator 160 occupies the fully forward position in the slot162 on the handle tip 42 (as FIG. 3 shows), the distal end of the sheath68 is generally coterminous with the end cap 74 of the mapping basket70. The distal end of the sheath 68 will thereby enclose the entiremapping basket 70 in a closed, collapsed condition.

When the physician subsequently moves the actuator 160 to the fullyrearward position in the slot 162 on the handle tip 42 (as FIG. 4shows), the distal end of the sheath 68 is generally coterminous withthe base member 72 of the mapping basket 70. This exposes the mappingbasket 70 for use. In this way, the second mechanism 32 is used todeploy and retract the mapping basket 70.

Preferably (as FIG. 26 best shows), the distal end of the flexible tube62 includes one or more O-rings or gaskets 164. The gaskets form a fluidtight seal between the flexible tube 62 and sliding sheath 68 to preventthe back flow of blood and other fluids from within the heart toward thecatheter handle 16.

C. The Mapping Assembly Shaping Mechanism

In the illustrated arrangement, the third mechanism 34 occupies the base40 of the handle. The proximal end of the control wire 78 of the mappingbasket 70 passes through the telescopic shaft for attachment within thesteering member 50 (see FIG. 25). The distal end of the control wire 78is attached to the basket end cap 74 (as FIG. 12 shows).

Fore and aft movement of the steering member 50 along the track 52thereby axial advances the control wire 78 to move the end cap 74 towardand away from the base member 72. This, in turn, expands, collapses, andshapes the mapping basket 70.

When the steering member 50 occupies the forwardmost position in thetrack 52 (as FIG. 7 shows), the end cap 74 is spaced farthest away fromthe base member 74. The flexible electrode support splines 78 lie in agenerally linear relationship between the base member 72 and the end cap74. The mapping basket 70 is in its closed or folded position, as FIG. 7shows.

When in this position, movement of the sheath control actuator 160 tothe forwardmost position in the tip slot 162 will serve to enclose thecollapsed mapping basket 70 completely within the sheath 68. Thecollapsed mapping basket 70 is thereby also retracted (as FIG. 3 shows).

Likewise, movement of the sheath control actuator 160 to itsrearwardmost position in the tip slot 162 will move the sheath 68 awayfrom the collapsed mapping basket 70. The mapping basket 70 is therebydeployed (as FIG. 4 shows).

When deployed, movement of the steering member 50 toward therearwardmost position in the track 52 will move the end cap 74progressively closer to the base member 72 (as FIGS. 5 and 6 show). Theresilient electrode support splines 78 progressively flex to assume aprogressively more bowed three dimensional shape. The shape of themapping basket 70 depends upon the position of the steering member 50within the track 52.

As the steering member 50 moves from the forwardmost position toward thecenter position of the track 52 (as FIG. 5 shows), the mapping basket 70will progressively change from an elongated, oval shape into a sphericalshape. As the steering member 50 moves further from the center positiontoward the rearwardmost position of the track 52, the mapping basket 70will progressively change from a spherical shape into a donut ortoroidal shape.

The third control mechanism 34 preferably includes an external lockingnut 166. Clockwise rotation of the locking nut 166 increases the seatingforce between the steering member 50 and the handle base 40. When movedfully clockwise, the locking nut 166 imposes a seating force thatprevents movement of the steering member 50 within the track 52. In thisway, the user can lock the mapping basket 70 in the desired shape, whileconducting other control or mapping operations.

Counterclockwise rotation of the locking nut 166 decreases the seatingforce and frees the steering member 50 for movement within the track 52.In this way, the user can manipulate the third mechanism 34 to open,close, and shape the mapping basket 70.

D. The Mapping Assembly 20 Twisting Mechanism

In the illustrated arrangement, the fourth mechanism 36 comprises therotating junction between the handle base 40 and the handle tip 42. AsFIG. 8 shows, by holding the handle tip 42 stationary, the user canrotate the main body 38 of the handle 16 relative to the tip 42. This,in turn, rotates the flexible tube 62, which is attached to the junctiontube 46 within the main handle body 38, as FIG. 10 shows. This rotatesthe mapping basket 70, which is attached to the flexible tube 62,without rotating the sheath (which is separately attached to thecarriage 60 within the handle tip 42, as FIG. 11 shows. In this way, thefourth control mechanism 36 rotates the mapping basket 70 withoutrotating the external sheath 68.

4. Deployable Preshaped Electrode Support Structures A. DeployablePreshaped Basket Assemblies

It should be appreciated that the mapping assembly 20 just describedneed not include a control mechanism for altering the basket's shape 70.The basket 70A can be preformed to collapse in response to an externalforce and to assume a single, prescribed final configuration upon theremoval of the external force.

In this arrangement the basket splines 78 are connected between the basemember 72 and the end cap 74 in a resilient, pretensed condition. Theresilient splines 78 collapse into closed, a compact bundle in responseto an external compression force.

In this embodiment, the second control mechanism 32 applies the force tocompress the basket 70. Movement of the tip actuator 160 to theforwardmost slot position advances the sheath 68 to compress andcollapse the basket 70 while enclosing it. Movement of the tip actuator160 to rearwardmost slot position advances the sheath 68 away from thebasket 70. This removes the compression force, and the freed splinesopen to assume a prescribed shape. In one preferred arrangement, atleast some of the individual splines 78 within the basket 70 includevarying regions of stiffness along their length. The varying regions ofstiffness deflect differently when commonly stressed. Thus, the spline,when bent, will not assume a uniform arc. Instead, the spline will bendin a nonuniform way, taking on a different shape. By locating splineshaving regions of varying stiffness in different regions of the array, amultitude of different prescribed shapes for the basket 70 can beobtained.

In another preferred embodiment, at least some of the splines includepreshaped memory wire like Nitinol. The memory wire assumes differentshapes, depending upon the temperature conditions surrounding it.

In this embodiment, when exposed to room temperature conditions outsidethe body, the memory wire splines assume a generally straightconfiguration. In this way, the splines can be collapsed into a compactshape for enclosure within the sheath 68 for placement within a heartchamber. When deployed outside the sheath 68 and exposed to internalbody temperatures within the heart chamber, the memory wire splineschange their generally straight configuration and assume anotherpredetermined shape.

These different arrays can be attached to the distal end of individual,specialized catheters and be deployed with a handle-mounted controlmechanism as previously described.

B. The Deployable Bladder Mapping Assembly

FIGS. 28 and 29 show an alternative mapping assembly 168 in which thesupport for the sensing electrodes takes the form of an inflatablebladder 170. The inflatable bladder 170 occupies the interior chamber174 of a base member 172, which the guide tube 62 carries at its distalend. The distal end of the base member 172 is open. As FIG. 28 shows,the bag 170 is normally stored at the distal end of the catheter orwithin the interior chamber 174 in a deflated, retracted condition.

A fluid pressure conduit 176 communicates with the bag 170. The conduitextends from the interior chamber 174 through the bore 64 of theflexible tube 62 to a port near the probe handle 16 (not shown in FIGS.28 and 29). In use, the physician connects the port to a source of fluidpressure, such as pressurized carbon dioxide or liquid saline solution.

After maneuvering the distal catheter end to the desired endocardiallocation, the physician conducts positive fluid pressure through thesupply conduit 176 into the bag 170. The positive fluid pressure causesthe bag 170 to expand or inflate.

The inflating bag 170 deploys outwardly beyond the open chamber end,assuming a prescribed three dimension shape (as FIG. 29 shows). Theshape can vary, depending upon the configuration of the bag. In theillustrated embodiment, the bag 170 assumes a somewhat spherical shapewhen inflated. Due to its pliant nature, the bag 170, when inflated,naturally conforms to the topography of the endocardial surface that isbeing mapped.

Release of the positive fluid pressure and the application of negativepressure through the supply conduit 176 will drain fluid from the bag170. The bag 170 collapses back into the base chamber 174 in a deflatedcondition (as FIG. 28 shows). Since the bag 170 deploys itself as itinflates, there is no need for a separate control mechanism to deploythe bag.

Alternatively, a movable sheath 68 controlled by the second mechanism 32(as earlier described) can be used to selectively enclose the bag 170before use and to free the bag 170 for use.

The bag includes an electrically conducting surface, such as platinum.The surface is applied, for example, using IBAD. The conductive surfacecan occupy the entire exposed area of the bag 170. In this case, thebag, when inflated, functions as a single sensing electrode 170.

Alternatively, the conductive surfaces can be applied in spaced zones178 upon the circumference of the bag 170 (as FIG. 29 shows). In thiscase, each zone 178 acts as an individual sensing electrode. The spacedconductive zones on the bag 170, when inflated, thereby togetherconstitute an array of sensing electrodes. The bag surface also carriesa solid state circuit applied by vapor deposition or similar technique.The circuit attached to signal wires 180 to conduct signals from theconductive zones to a microconnector 92 in the base 172. These signalsare in turn transmitted along the length of the associated catheter inthe manner already described.

C. Deployable Sail Mapping Assembly

FIGS. 30A and 30B show another alternative mapping assembly 182. In forthe sensing electrodes takes the form of a resilient body 184 thatresembles a sail. The sail body 184 is preferable made of a resilientrubber or elastomeric material.

The assembly 182 includes a base member 186 with an interior chamber 188having an open distal end. The guide tube 62 carries the base member 186at its distal end.

A control wire or shaft 190 is attached to the backside of the sail body184. The control wire 190 is movable along the axis of the guide tube 62in response to a handle mounted control mechanism, like the control wire78 associated with the variable size mapping basket shown in FIG. 12. Inthe illustrated embodiment, the handle mounted control mechanism canaffect the same fore and aft movement of the steering member 50 upon thehandle base 40, as previously described.

In this arrangement, when the steering member 50 occupies therearwardmost position in the track 52, the sail body 184 is drawn backwithin the base chamber 188 (as FIG. 30B shows). In this condition, thesides of the resilient sail body 184 fold forwardly upon the side wallsof the chamber 188, and the sail body 184 assumes a folded, concaveshape within the confines of the base chamber 188. The mapping assembly182 is retracted in this condition.

Subsequent movement of the steering member 30 toward the forwardmostposition in the track 52 urges the sail body 184 out of the chamber 188.Freed from the confines of the chamber 188, the sides of the sail body184 resiliently spring into an open, convex shape, as FIG. 30A shows.The mapping assembly 20 is deployed in this condition.

Movement of the steering member 50 back toward the rearwardmost positionin the track 52 urges the sail body I84 back into the confines of thebase chamber 188. In the process, the resilient sides of the sail body184 will again fold forwardly against the side walls of the chamber 188.

The sail body carries one or more sensing electrodes 192. The electrodes192 can be physically attached to the sail body 184. Alternatively, theelectrodes can be applied, for example, using IBAD.

The sail electrode array 182 is ideally suited for endocardial mapping.Like the previously described bag array 68 (shown in FIGS. 28 and 29),the deformable, elastic sail body 184 will readily conform to thetopography of the endocardial surface that it is pressed against formapping.

A hard wire or solid state circuit on the sail body 184 attaches tosignal wires 194 to conduct signals from the electrodes 194 to amicroconnector 92 in the base 186. These signals are in turn transmittedalong the length of the catheter in the manner already described.

D. Deployable Radial Bundle Mapping Assembly

FIGS. 31A; 31B; and 31C show yet another alternative mapping assembly196. In this embodiment, the support for the sensing electrodes includesa center spine 198 from which an array of flexible support filamentsradiate. Each support filament carries a sensing electrode 202.

As before, the assembly includes a base 204 with an interior chamber 206having an open distal end. As before, the guide tube 62 carries the base204 at its distal end.

The center spine 198 is movable along the axis of the guide tube 62 inresponse to the operation of a handle mounted control mechanism. In theillustrated embodiment, fore and aft movement of the steering member 50,as previously generally described, can serve this control function.

In this arrangement, when the steering member 50 occupies therearwardmost position in the track 52, the mapping assembly 200 isretracted and the filament array 196 is drawn back within the basechamber 206, as FIG. 31A shows. In this condition, each filament 200 isfolded against the side walls of the chamber 206.

Subsequent movement of the steering member 50 toward the forwardmostposition in the track 52 urges the central spine 198 out of the chamber206. Freed from the confines of the chamber 206, the support filaments200 spring into an open, three dimensional array radially surroundingthe center spine 198, as FIG. 31B shows. The mapping assembly 20 is thusdeployed.

Movement of the steering member 50 back toward the rearwardmost positionin the track 52 urges the center spine 198 back into the confines of thebase chamber 206. In the process, the flexible filaments 200 foldforwardly against the side walls of the chamber 206, as FIG. 31C shows.

The radial bundle of filaments 200, each carrying a sensing electrode202, offers a high density, random mapping array 196. The flexiblenature of the random array 196 readily conforms to the topography of theendocardial surface that it is pressed against.

A hard wire or solid state circuit on the filaments 200 and center spine198 conducts signals from the individual electrodes 202 to amicroconnector 92 in the base 204. These signals are in turn transmittedalong the length of the catheter in the manner already described.

E. Deployable Foam Tip Mapping Assembly

FIGS. 32A and 32B show still another alternative mapping assembly 208.In this embodiment, the support for the sensing electrodes takes theform of a porous foam body 210.

As before, the assembly 208 includes a base 212 with an interior chamber214 having an open distal end. As before, the guide tube 62 carries thebase 212 at its distal end.

Like the foregoing alternative embodiments, the foam body 210 isdeployed from within the interior chamber 214. The foam body 210 ismolded to assume what can be called a normal shape. In the illustratedembodiment (as FIG. 32A shows), the normal uncompressed shape isgenerally spherical. However, the original uncompressed shape can berectangular, square, oval, toroid, or virtually any other shape.

Due to its porous, open structure, the body 210 can be collapsed,without damage, by an external compression force into another morecompact shape. In the illustrated embodiment (as FIG. 32B shows), themore compact shape is generally cylindrical, to fit within the confinesof the base chamber 214. However, other compact shapes can be used. Whenthe external compression force is released, the porous foam bodyresilient returns to its normal shape.

A control wire or shaft 216 is attached to the foam body 210. Thecontrol wire 216 is movable along the axis of the guide tube 62 inresponse to the operation of a handle mounted control mechanism. In theillustrated embodiment, fore and aft movement of the probe steeringmember 50 can control the wire.

In this arrangement, when the steering member 50 occupies therearwardmost position in the track 52, the foam body 210 is drawn backwithin the base chamber 214, as FIG. 32B shows. The side walls of thebase chamber 214 compress and collapse the foam body 210. When socompressed, the foam body 210 conforms to the interior shape of basechamber 214. The mapping assembly 208 is retracted.

Subsequent movement of the steering member 50 toward the forwardmostposition in the track 52 urges the foam body 210 out of the chamber 214,as FIG. 32A shows. When freed from the confines of the chamber 214, thefoam body 210 opens into its normal uncompressed shape. The mappingassembly 208 is deployed.

Movement of the steering member 50 back toward the rearwardmost positionin the track 52 urges the foam body 210 back into the confines of thebase chamber 214. The foam body 210 is again compressed into a compact,retracted shape, as FIG. 32B shows.

The foam body 210 carries one or more sensing electrodes 218. Theelectrodes 218 can be physically attached to the foam body 210.Alternatively, the electrodes 218 can be applied, for example, usingIBAD. The sensing electrodes 218 constitute a high density array ideallysuited for endocardial mapping.

A hard wire or solid state circuit on the foam body 210 conducts signalsfrom the electrode zones 218 to a microconnector 92 in the base 212.These signals are in turn transmitted along the length of the catheterin the manner already described.

5. Dynamic Mapping Assemblies

FIGS. 33 to 36 show a mapping assembly 220 that dynamically alters itsshape to compensate for the compression of the heart chamber in which itis located.

The mapping assembly 220 includes a base member 222 that is attached tothe distal end of the guide tube 62, as previously described (see FIG.34). The mapping assembly 220 includes an array of resilient electrodesupports 224. Their proximal ends are attached to the base 222, andtheir distal ends are attached to a end cap 226.

As described, this mapping assembly 220 is identical to the mappingassembly 20 shown in FIG. 12. As in FIG. 12, the mapping assembly 220can include a movable sheath 68 and an associated control mechanism 32for alternatively enclosing and deploying the assembly 220.

During endocardial mapping, the heart muscles continuously expand andcontract with the beating of the heart. When deployed, the mappingassembly 220 will thereby be subject to alternate cycles of contractionand expansion. The surface pressure of the sensing electrodes 228against the moving endocardium can therefore continuously vary,complicating the task of accurately recording the potentials. Thesensing electrodes can also slip along the constantly moving endocardialsurface.

To counteract this phenomenon, the mapping assembly 220 includes means230 for continuously urging the sensing electrodes 228 against theendocardium and for maintaining a constant surface pressure, despitecontraction and expansion of the heart.

The means 230 can vary. In the illustrated embodiment, the base member222 includes a tubular body that carries a front movable mount 232 and afixed rear mount 234 (best shown in FIGS. 33 and 35). The interior sidewall 236 of the base member 222 serves as a bearing surface for themovable mount 232. The movable mount 232 carries the proximal ends ofthe electrode supports 224.

A spring 238 connects the front mount 232 to the rear mount 234. Thefront mount 232 moves toward the rear mount 234 when the electrodesupports 224 experience compression within the heart chamber (as FIGS.33 and 34 show). The reverse is true when the electrode supports 224experience contraction within the heart chamber (as FIGS. 35 and 36show).

Movement of the front mount 232 toward the rear mount 234 compresses thespring 238. When compressed, the spring 238 urges the front mount 232toward a distal position within the base 22, in which the spring 238 isnot compressed.

The mounts 232/234 and spring 238 thereby establish an dynamic junctionbetween the electrode supports 224 and the endocardium. Contraction ofthe heart chamber surrounding the mapping assembly 220 exerts acompression force on the electrode supports 224. The front mount 232moves toward the rear mount 224 in response to this compression. Thespring 238 serves to dampen and resist this movement, holding theelectrodes against the endocardium.

When the heart chamber expands, the spring 238 urges the front mount 232forward, urging the electrode supports 224 back toward their originalshape.

The spring thereby maintains contact between the electrode supports 224and the surrounding, moving endocardium.

In the illustrated and preferred embodiment, the spring 238 has a fixedspring constant that does not vary with compression. In other words, thespring 238 is a constant force spring.

The constant force spring 238 can take various forms. In the illustratedembodiment (as FIGS. 33 and 35 best show), the spring 238 is a conicalspring. When compressed, it exerts a constant force, regardless of thedegree of compression.

The constant force 238 spring establishes and maintains a constantsurface pressure between the mapping assembly 220 and the surroundingendocardium. The dynamic junction established produces consistentlyaccurate readings during periods of contraction and expansion of thesurrounding heart muscle.

It should be appreciated that the dynamic junction can be used inassociation with mapping assemblies of various sizes and shapes. It isnot limited in use with the particular basket mapping assembly 220 shownin FIGS. 33 to 36.

6. Mapping Site Flushing and Coagulation Control

According to another aspect of the invention, the mapping assembly canincludes means for conveying fluid to the mapping site.

The fluid conveying means can vary. In the embodiment shown in FIG. 12,the mapping assembly 20 includes a flexible central tube 240 surroundingthe control wire 78. The tube 240 extends from the end cap 74, throughthe base member 72 and bore of the flexible tube 62 to a fluid port 242(like that shown in FIG. 26). Fluid to be conveyed to the site isintroduced under pressure through the port 242.

The end cap 74 includes a center channel 244 communicating with thedistal end of the tube 240. Fluid conveyed by the tube 240 exits throughthe channel 244 into the mapping site.

Preferably, the center channel includes a valve 246, similar to valve156 shown in FIGS. 27 and 27A. The valve 246 blocks the passage offluids from the tube 240 through the channel 244 under the influence ofthe in vivo diasole and systole pressures. The valve 246 thereby blocksblood and other fluids present within the heart chamber from enteringthe tube and the interior regions of the catheter.

The valve 156 opens in response to higher pressures to enable theintroduction of fluids from an external source through the guide tube154 into the heart. In this arrangement, the pressure at which fluid isconveyed through the catheter into the heart chamber through the valve246 is greater than the normal in vivo pressures generated during heartsystole and diastole. The fluids so introduced wash the region aroundthe mapping basket 170.

The fluid can be, for example, saline and be used to flush the mappingsite to keep the sensing electrodes free of tissue buildup and blood.The fluid can also be heparin or another anticoagulant and be used toactively reduce the incidence of coagulation during the mappingprocedure.

This flushing action clears blood and other body fluids away from theelectrodes carried by the basket 170, so that reliable signals can beobtained and/or the desired ablation energy can be applied, withoutattentuation.

Various features of the invention are set forth in the following claims.

What is claimed is:
 1. A probe for cardiac diagnosis and treatmentcomprising:a catheter having a distal end for insertion into a heartchamber, means on the distal end of the catheter comprising an array ofradially extending splines, each spline having a proximal end and adistal end and supporting at least one electrode, a fluid flow conduitextending through the catheter for conducting fluid from an externalsource through the catheter distal end, and valve means at the catheterdistal end for preventing fluid flow from the heart chamber into theconduit while permitting the fluid flow through the conduit into theheart chamber wherein the distal ends of the splines are connected to anend cap, and wherein the fluid flow conduit extends through the end cap.2. A probe according to claim 1 wherein the valve means is locatedwithin the end cap.
 3. A probe according to claim 1 wherein the valvemeans prevents fluid flow from a heart chamber into the conduit inresponse to in vivo pressure generated during heart systole and diastolewhile permitting fluid flow from the conduit into a heart at a pressureabove the in vivo pressure.
 4. A probe according to claim 1and furtherincluding a guide wire extending through the catheter for guiding thecatheter, wherein the guide wire extends through the valve means beyondthe catheter distal end, and wherein the valve means sealingly surroundsthe guide wire.
 5. A system for cardiac diagnosis and treatment furthercomprising:a catheter having a distal end for insertion into a heartchamber, means on the distal end of the catheter comprising an array ofradially extending splines, each spline having a proximal end and adistal end and supporting at least one electrode, a fluid flow conduitextending through the catheter for conducting fluid from an externalsource through the catheter distal end, and valve means at the catheterdistal end for preventing fluid flow from the heart chamber into theconduit while permitting the fluid flow through the conduit into theheart chamber wherein the distal ends of the splines are connected to anend cap, and wherein the fluid flow conduit extends through the end cap,a pressurized source of fluid and means for connecting said source offluid to said fluid flow conduit.
 6. A system according to claim 5wherein said pressurized source of fluid comprises heparin.
 7. A systemaccording to claim 5 wherein said pressurized source of fluid comprisessaline solution.
 8. A system for cardiac diagnosis and treatmentcomprising:a pressurized source of fluid, a catheter having a distal endfor insertion into a heart chamber, means on the distal end of thecatheter for supporting at least one electrode, a fluid flow conduitconnected to said to said source of fluid and extending through thecatheter for conducting fluid from the source through the catheterdistal end to flush the area surrounding the electrode, and valve meansat the distal catheter end for preventing fluid flow from a heartchamber into the conduit in response to in vivo pressure generatedduring heart systole and diastole while permitting fluid flow from theconduit into said heart chamber at a pressure above the in vivopressure, and further including a guide wire extending through thecatheter for guiding the catheter, wherein the guide wire extendsthrough the valve means beyond the distal catheter end, and wherein thevalve means sealingly surrounds the guide wire.